It is an important consideration in this type of missile application that the homing mechanism which is located at the forward end of the torpedo be protected from damage throughout the mission environment, i.e., when fired from the launching canister, during airborne flight to the target area, and upon water impact and entry. Damage to the torpedo homing mechanism during any portion of the mission will obviously result in defeat of the torpedo performance and, thus also, a defeat of the entire mission.
U.S. Pat. No. 4,788,914 issued Dec. 6, 1988 to James T. Frater describes a missile nosepiece comprised of a frangible base member and a separable nosecap, the base comprised of multiple segments of rigid foam defining an axial bore and a volume of soft cellular foam within the bore to protect the forward end of the torpedo which houses the torpedo homing mechanism. The nosecap is mounted to the base member is such a manner that it may be separated from the base prior to water entry such as to expose the central bore into the frangible base member. Upon water impact, the force of the water entering the exposed central bore effects fracturing of the base and it is separated from the forward end of the torpedo.
The above-described missile nosepiece of the prior art depends for its successful operation upon a separation of the nosecap from the base prior to water impact so as to expose the central bore into the frangible base. If, for some reason the nosecap does not fall away from the base before water impact, then fracturing of the base member will not be effected and the nosepiece will remain on the forward end of the homing torpedo. Obviously, this will impede the operation of the homing mechanism. It should also be clear that the nosecap must be separated from the base member at an altitude and in time before water impact so that a water force of sufficient magnitude enters the base central bore and/or is generated within the central bore to effect fracturing of the base member. Thus, even if the nosecap is removed from the frangible base member, sufficient water impact forces must be generated to fracture the base so that it may be separated from the forward end of the homing torpedo.